The optical elements of the eye include both a cornea (at the front of the eye) and a lens within the eye. The lens and cornea work together to focus light onto the retina at the back of the eye. The lens also changes in shape, adjusting the focus of the eye to vary between viewing near objects and far objects. The lens is found just behind the pupil, and within a capsular bag. This capsular bag is a thin, relatively delicate structure which separates the eye into anterior and posterior chambers.
With age, clouding of the lens or cataracts are fairly common. Cataracts may form in the hard central nucleus of the lens, in the softer peripheral cortical portion of the lens, or at the back of the lens near the capsular bag.
Cataracts can be treated by the replacement of the cloudy lens with an artificial lens.
Phacoemulsification systems often use ultrasound energy to fragment the lens and aspirate the lens material from within the capsular bag. This may allow the capsular bag to be used for positioning of the artificial lens, and maintains the separation between the anterior portion of the eye and the vitreous humour in the posterior chamber of the eye.
During cataract surgery and other therapies of the eye, accurate control over the volume of fluid within the eye is highly beneficial. For example, while ultrasound energy breaks up the lens and allows it to be drawn into a treatment probe with an aspiration flow, a corresponding irrigation flow may be introduced into the eye so that the total volume of fluid in the eye does not change excessively. If the total volume of fluid in the eye is allowed to get too low at any time during the procedure, the eye may collapse and cause significant tissue damage. Similarly, excessive pressure within the eye may strain and injure tissues of the eye.
While a variety of specific fluid transport mechanisms have been used in phacoemulsification and other treatment systems for the eyes, aspiration flow systems can generally be classified in two categories: 1) volumetric-based aspiration flow systems using positive displacement pumps; and 2) vacuum-based aspiration systems using a vacuum source, typically applied to the aspiration flow through an air-liquid interface. These two categories of aspiration flow systems each have unique characteristics that render one more suitable for some procedures than the other, and vice versa.
Among positive displacement aspiration systems, peristaltic pumps (which use rotating rollers that press against a flexible tubing to induce flow) are commonly employed. Such pumps provide accurate control over the flow volume. The pressure of the flow, however, is less accurately controlled and the variations in vacuum may result in the feel or traction of the handpiece varying during a procedure. Peristaltic and other displacement pump systems may also be somewhat slow.
Vacuum-based aspiration systems provide accurate control over the fluid pressure within the eye, particularly when combined with gravity-fed irrigation systems. While vacuum-based systems can result in excessive fluid flows in some circumstances, they provide advantages, for example, when removing a relatively large quantity of the viscous vitreous humour from the posterior chamber of the eye. However, Venturi pumps and other vacuum-based aspiration flow systems are subject to pressure surges during occlusion of the treatment probe, and such pressure surges may decrease the surgeon's control over the eye treatment procedure.
Different tissues may be aspirated from the anterior chamber of the eye with the two different types of aspiration flow. For example, vacuum-induced aspiration flow may quickly aspirate tissues at a significant distance from a delicate structure of the eye (such as the capsular bag), while tissues that are closer to the capsular bag are aspirated more methodically using displacement-induced flows.
Conventionally, fluid aspiration systems include a console and a fluidic cassette mounted on the console. The fluidic cassette is typically changed for each patient and cooperates with the console to provide fluid aspiration. Generally, a single type of cassette is used by a particular console, regardless of whether the procedure will require positive displacement aspiration, vacuum-based aspiration, or both. U.S. Pat. No. 8,070,712; U.S. Published Application 2008011431; and U.S. Published Application 20080114291 provide examples of cassettes currently used in the marketplace, the contents of each are herewith incorporated by reference in their entirety as if set forth herein.
Such a cassette is typically physically mated to the afore-discussed console. In providing the physical association between the cassette and the console, at least the aspiration/pumping aspects discussed above must be properly aligned as between the cassette and the console, at least in order to provide proper functionality to the fluidics systems. As such, misalignment may lead to system malfunction, inoperability, or poor performance. However, currently available systems that provide for the alignment of placement and attitude of the cassette onto the console suffer from a variety of issues, including jamming, breakage, and inability to assess a sound alignment and cassette attitude, among others.
More particularly, the surgical cassette may be inadvertently or deliberately mis-loaded into the receiving interface of the console. This mis-loading may occur in such a way so as to cause jamming of the cassette between the side-clamps that are interior to the receiving area of the console and are provided to receive the cassette. A mis-load may particularly occur when the planar attitude of the cassette is tilted rotationally toward the left or right of the receiving area of the console. Although misalignment occurs less frequently as expertise in use of the console increases, even the most expert users experience an occasional mis-load.
In the known art, alignment features may thus be provided, such as an “alignment key” on one of the console receiving area or the cassette, or exterior clamps, such as on the exterior portion of the console and on the top and bottom of the receiving area. However, these solutions in the known art still frequently suffer from jamming due to misalignment, such as due to inadvertent misalignment of the alignment key or improper orientation with respect to one of the top clamp or the bottom clamp. Additionally, these solutions fail to provide suitable for handling of the administration tubing that typical provides the fluid aspiration discussed above.
In light of the above, it would be advantageous to provide improved devices, systems, and methods for eye surgery.